1. Technical Field
This invention relates generally to the use of a sorbent material to sorb liquids. Particularly, this invention relates to the use of processed tropical fibers, such as banana, plantain, cavendish plant, pineapple, coconut, and palm, to recover spilled oil, gasoline, kerosene, solvents, hydrocarbons, pentachlorophenol (PCP), creosote or other liquids.
2. Description of the Prior Art
Spills of oil, solvents and hazardous materials are a continuing problem having serious environmental consequences, including damage to the oceans, beaches, inland rivers, streams and creeks, as well as detrimental effects upon the health of wildlife and humans. The need for oil and chemical products has created consistent growth in the chemical industry, including the transport and manufacturing of these compounds, resulting in increasing environmental problems associated with spills, accidents and improper disposal.
Sorbent materials, including both materials that absorb and materials that adsorb, have been used for many years in the cleanup of oil and hazardous materials by private industry and the federal government. Sorbent clay materials are currently the material of choice for absorbing or recovering oil or other hazardous chemicals on land. In industrial applications, these materials have the disadvantages of low sorbent capacity and a high density which make them both heavy and difficult to transport. Additionally, the abrasiveness and friability of these products may lead to increased wear of nearby industrial machinery. These clay based sorbents are not biodegradable and, therefore, pose an additional environmental problem because they must be disposed of in the limited space available in landfills. Peat, diatomaceous earth and vermiculite are sometimes used as alternatives to the clay based sorbents.
The primary sorbents used in remediation of spills of oil or other hazardous substances on water consist of synthetic materials such as polypropylene, which is currently the product of choice for industry and remediation specialists. However, since polypropylene is itself a synthetic chemical, its production handling can be the source of other environmental problems. Additionally, because these synthetic sorbents are not biodegradable and currently must be disposed of in landfills, they increase the load on the limited available landfill capacity. Therefore, a need exists for an efficient natural sorbent material which is not a source of environmental problems.
One process for alleviating the environmental problems associated with the production of oil or chemical sorbent materials is to use a sorbent system based on natural fibers. Over the last several decades, a wide variety of treated natural fibers have been used as sorbents of hazardous materials. These have included tree bark, peat, wood fiber, dealginate kelp, powdered lily, kenaf cores, puffed cereals, and a variety of other cellulosic materials. Each of these fiber types has disadvantages which have prevented them from becoming the material of choice for remediation of oil and chemical spills on land or in water.
The primary disadvantage of most of these fiber types is that they are naturally hydrophilic and, therefore, tend to sorb large quantities of water. Sorption of water increases the weight of these materials and can seriously decrease their ability to sorb the oil or hazardous chemical which these materials are intended to recover. It is possible to reduce or eliminate the tendency of some of these materials to sorb water by treatment with chemical additives to increase their hydrophobicity.
For example, in U.S. Pat. No. 5,021,390, Hatton teaches a composition for sorbing liquids consisting of various fibrous plant materials treated with the waterproofing agent sodium methyl silicate. In U.S. Pat. No. 5,492,881, Diamond teaches a sorbent system using finely ground cellulose treated with a hydrophobic agent such as paraffin, other waxes, polyvinyl alcohol, hydroxyethyl cellulose or the like. These additives add to the manufacturing expense of the sorbent and may themselves be the source of further harm to the environment.
Another disadvantage of previously disclosed natural fiber based sorbents is that most are generally only capable of sorbing 5-10 times their mass in oil or other chemicals. Additionally, most of these natural fiber compositions have a tendency to sink as they become saturated with oil, water or other chemicals, making recovery of these materials and sorbed chemical from a body of water extremely difficult or impossible.
Several of the previously disclosed fiber compositions are not readily biodegradable which poses a potential environmental problem since these fibers will not easily degrade when disposed of in a landfill. For example, in U.S. Pat. No. 3,791,990, Fischer et al. teach an oil sorbent material composed of peat fibers dried to less than 10% by weight water. These fibers are believed not to be biodegradable, which, although beneficial from the stand point of reducing leaching of the liquids, results in a long lifetime in landfills. Overuse of the limited landfill capacity is a major environmental problem, and it is therefore desirable to provide a sorbent material which is readily biodegradable after use and recovery of the oil, solvent or other liquids.
Presently, banana stalks, plantain stalks, cavendish plant stalks, pineapple crowns, palm, palmetto and coconut fronds, and a variety of other tropical plant portions are thought of as waste agricultural byproducts in the countries in which they are produced. Currently these byproducts are disposed of in landfills, where they can attract insects and contribute to landfill capacity problems. Additionally, they may be discarded into rivers, where they oxidize and can cause potential environmental problems. In other instances, the byproducts are left on the ground to act as a natural fertilizer.